Problem: $\dfrac{6}{10} - \dfrac{8}{5} = {?}$
Answer: $ = {\dfrac{6 \times 1}{10 \times 1}} - {\dfrac{8 \times 2}{5 \times 2}} $ $ = {\dfrac{6}{10}} - {\dfrac{16}{10}} $ $ = \dfrac{{6} - {16}}{10} $ $ = -\dfrac{10}{10}$